Bounding mass drilling tool



April 28, 1964 P. s. WILLIAMS 3,130,799

BOUNDING MASS DRILLING TOOL Filed Jan. 6, 1961 y s Sheets-Sheet 1 FIG. 1

. Philip s. wfi liljoms Inventor y t. Qa-ai. Attorney April 1964 P. s. WILLIAMS 3,130,799

BOUNDING MASS DRILLING TOOL Filed Jan. 6, 1961 3 Sheets-Sheet 2 Philip S. Williams I lnvenio By a. Q-L Attorney April 28, 1964 s. WILLIAMS 3,130,799

' BOUNDING MASS DRILLING TOOL Filed Jan. 6, 1961 3 Sheets-Sheet 3 Philip S. Williams lnyento'r By t. 0-...L. Attorney United States Patent 3,130,799 BOUNDING MASS DRILLING TOOL Philip S. Williams, Tulsa, Okla, assignor to Jersey Production Research Company, a corporation of Delaware Filed Jan. 6, 1961, fier. No. 81,066 3 Claims. (ill. 175-92) The present invention is broadly concerned with the art of drilling boreholes in the earth and is more especially concerned with an improved fluid-actuated impact tool designed for use in drilling such boreholes. The tool is particularly characterized by novel means for periodically and repeatedly lifting and then impacting a drill bit against a rock surface being drilled.

In present day practice, a large proportion of the boreholes drilled into the earth are drilled by the rotary method. In carrying out this method, a string of drill pipe provided with a bit at its lower end is first run into the borehole. The drill string is then rotated from the surface to disintegrate the formation beneath the bit. The drill bits normally used in such operations include drag bits, roller cone bits, and the like. These bits, or more specifically their cutting elements, depend primarily for their drilling action either upon a scraping or grinding action as they are rotated on the bottom of a borehole. A drilling fluid is circulated down through the drill pipe and back through the annulus between the drill pipe and the wall of the hole to remove the broken rock or cuttings and to seal the wall of the hole.

A substantial portion of the expense incurred in rotary earth drilling is due to the low penetration rates ob ained with conventional tools. This is especially true in hard abrasive formations, since the rotary system is characterized by rotation of the bit under static load. When hard abrasive formations are encountered, the bit may advance at the rate of a foot per hour or less. This slow rate is attributed to the inability of the bit to penetrate into or crush the formation immediately beneath the cutting elements and thus only a scraping or grinding action is utilized in disintegrating the formation. As a consequence, only small fragments of the formation are removed with each rotation of the bit.

T o alleviate the shortcomings of standard rotary drilling practices, especially in hard abrasive formations, percussive type drilling methods and tools have been developed. Most of these tools are based on a hammer and anvil concept. A hammer in the tool strikes an anvil which in turn is connected to a drill bit that is in contact with the formation being drilled. The impact force available from such drilling tools is considered to be proportional to the Weight of the hammer, the frequency of the blows of the hammer and the distance of travel of the hammer. To obtain a maximum impact force, most percussive oil well drilling tools have been designed with low hammer weight, with a short distance of travel for the hammer, and with a high number of blows of the hammer per unit of time. As an example, presently developed compressed-air-operated drilling tools use hammers weighing only a few pounds, traveling only a few inches and supplying percussive blows at a frequency of 1400 to 3000 blows per minute.

The percussive tools presently used have been successful in increasing drilling rates in terms of feet of formation penetrated per hour of drilling. Unfortunately, however, these tools utilize complicated mechanical and/ or electrical equipment that has a high wear factor, primarily due to the high frequencies of operation. Therefore, instead of achieving decreased drilling costs and despite the higher drilling rates, the use of these tools has frequently resulted in increased drilling costs.

3,130,799 Patented Apr. 28, 1964 "ice Therefore, one of the objects of the present invention is to provide a rotary drilling tool whereby drill bit cutters cooperatively penetrate into or crush a formation to provide for more efiicient and economical means of drilling boreholes into the earth. Another object of the invention is to provide a percussion type drilling tool which is adapted to be used in conjunction with conventional rotary drilling equipment and which will deliver a high impact force onto the face of the rock at relatively low frequency and velocity of impact. Other objects and features of this invention will become more apparent from the following written description and the attached drawing in which:

FIGURE 1 is a longitudinal sectional view of the major components of a drilling apparatus which embodies this invention and which is contemplated to constitute the best mode of carrying out the invention;

FIGURE 2 is a sectional view illustrating the upper components of the drilling apparatus;

FIGURE 3 is a section along lines AA of FIG- URE 1;

FIGURE 4 is a section along lines B-B of FIGURE 1; and v FIGURE 5 is a section along lines C-C of FIG- URE 2.

Referring to FIGURE 1, the drilling tool includes cutting elements or drill bits 1 and 7 which cooperatively act to drill a borehole into the earth. These elements, as shown, depict what is conventionally designated as a star type drilling bit. However, this invention may be practiced with other types of drill hits, such as roller cone types, drag types, and the like.

Element 1 is connected by threaded joint 35, or what is better known in the art as a tool joint, to cylindrical pipe sub member 2. A hole in the wall of sub 2 is threaded to receive a closing pipe plug 22. A lubricating fluid may be introduced through this hole into the annular space between sub 2 and member 43. The upper end of sub 2 is connected to tubular drill collar 3 as by means of joint 31. Drill collar 3 is in turn connected to cylindical pipe sub 4 which has a semi-pipe cap 36 threadably connected to it at its upper end. Semi-pipe cap 36 serves to retain upper tubular member or sub 5 within sub 4.

Central cutting element or bit '7 is connected as by a. threaded tool joint 37 to cylindrical pipe sub 8. Included in sub 8 are two O-Iing seals or equivalent sealing elements 38, which seal between the inner surface of member 2 and the outer surface of sub 8. Shoulder 20 on the upper end of sub 3 is in contact with a corresponding shoulder 39 on the inner surface of member 2.

Sub member 8 is threadably connected to cylindrical member 43. Members 8 and 43 are considered in this instance as an inner mass or lower tubular member slidably connected to sub member 2. Near the lower end of member 43 is an extension 41 which mates with corresponding recesses 42 on the inner surface of member 2 to provide a slidable spline shaft 19. Member 2 in this same region has ports or fluid orifices 18 to prevent an entrapment of fluid in the annular spaces between sub 43 and sub 2. Without the orifices, a fluid lock could develop to prevent separate upward or downward movement of the subs.

The parts which make up spline joint 19 for slidably connecting members 2 and 43 may be better understood by referring to FIGURE 3 which shows section AA of FIGURE 1. Joint 19 is an optional but preferred feature, since frictional forces between close fitting members 8 and 43 inside member 2 would be sufiicient for rotation of bit 7, especially when the bit is off the bottom of the hole as described later.

Referring back to FIGURE 1 and member 43, coil spring surrounds member 43 in the annular space between sub 2 and member 43. On the upper end of member 43, which is enlarged to fit with a close tolerance in sub 2, may be seen O-rings or equivalent sealing elements 44. Tapered valve seat 17 on the upper end of member 43 is immediately adjacent piston face 9.

Positioned immediately above valve seat 17 is valve plug 11. Valve plug 11 is connected as by a threaded joint 60 to valve stem 14 which has an enlarged section to retain the stem in valve bracket or housing 13. Surrounding stem 14 is valve spring 16. Bracket 13 is shown positioned in a recessed section of member 2, and is held in place by a spacer 45 which has its upper end resting on the outer peripheral surface of shoulder 15 comprising the lower end of tubular conduit drill collar 3.

Included in bracket 13 are ports 12 which allow drilling fluid to circulate through this assembly. Ports 12 are also shown in FIGURE 4.

The lower section of FIGURE 2 shows a continuation of the drill collar 3 which is also shown in the upper part of FIGURE 1. Although only one such drill collar is illustrated, a drill collar string-4e. a plurality of drill collarsmay also be used at this point in the tool. Drill collars or tubular conduits of this nature are made of steel, weigh about to 80 pounds per foot and are usually 10, 20 or 30 feet in length.

An elongated cylindrical tubular part of sub 5 fits snugly in pipe sub 4 which contains recesses in which are placed sealing elements such as O-rings 48. The elongated part and the sealing elements permit up and down movement of sub 5 with respect to sub 4 and maintain a fluid-tight passageway through the bores of these subs.

A spline shaft containing recesses and extensions 49 is shown on the inner part of sub 4. These recesses and extensions engage with recesses and extensions 50 on the outer enlarged part of sub 5. The relation of these members is more readily apparent in FIGURE 5. Sub 5 is also connected by a threaded tool joint 33 to tubular conduit drill pipe 6.

Fluid ports 52 and 53 in the upper part of tubular sub 4 serve to restrict the flow of drilling fluid from the annular space between subs 4 and 5. These ports prevent entrapment of fluid in this annular area which could cause a fluid lock to develop between these moving parts. Some dampening effect also occurs.

The operation of the tool described above can best be understood by first tracing the flow of drilling fluid through the apparatus. As in conventional operations, drilling fluid is circulated from the surface of the earth by conventional pumps through conventional surface equipment and thence down through the passageway 55 or the bore of drill pipe 6 shown in FIGURE 2. The drilling fluid then continues downwardly through the bore of sub 5, through sub 4 and through passageway 30 in drill collar 3. Fluid flows from passageway 30 through fluid ports 12 provided in bracket 13, through the opening between valve plug 11 and valve seat 17, through the bore of sub 13 and sub 8 and is discharged through fluid ports 60 of bit 7 to the bottom of the hole. The drilling fluid thus discharged picks up cuttings and carries them back up the annulus between the drill string and the borehole wall to the earths surface.

In operating the apparatus, the drilling tool is sus pended above the bottom of the borehole and drilling fluid is circulated from the surface to the tool. Rotation of the drill pipe is initiated. The tool is then dropped on the bottom of the borehole. On impact, plug 11 moves down very rapidly due to its inertia. The pres sure difference above the upper face of plug 11 and below the lower face of plug 11 due to the high rate of fluid flow through the orifice outlined by valve plug 11 and valve seat 17 augments the inertial forces. This pressure difference is commonly called the Bernoulli effect. Plug 11 seats on valve seat surface 17 in response to the inertial and Bernoulli forces. If desired, the tool can be designed so that Bernoulli forces alone are sufficient to initiate operation of the tool.

When valve plug 11 closes, there is an instantaneous stoppage of mud flow which results in the generation of a water hammer compression Wave that travels up the column of mud. This compressional wave causes a high pressure to be impressed downwardly on piston face 9 to drive the cutting element of inner bit 7 against the bottom of the hole. A reaction force acts on shoulder 15 of drill collar 3. The force acting on shoulder 15 causes the outer case assembly or impact mass sleeve consisting of members 2, 3, and 4 and drill bit 1 to accelerate in an upward direction. The entire drill string does not move upwardly, since the slidable connection spline joint, comprising elements 49 and 519, permits relative movement of the outer assembly without interference from drill pipe 6. Furthermore, the slidable joint 19 allows the inner assembly or tubular shaft to remain stationary. When this outer case assembly moves upward, spring M is compressed and bit '7 remains on the bottom of the bore hole due to pressure on shoulder 9.

This assembly will rise until a reflection of the hammer wave from passageway 30 in tubular drill collar 3 to larger passageway 55 in drill pipe 6 permits spring 16 to lift valve plug 11 off of seat 1'7. A positive pulloff of plug valve 11 is provided by the upper movement of the outer assembly and by force from spring 16 which has been compressed by upward movement of this assembly. Drilling fluid flow will then be re-established and pressure will be essentially equalized above and below the orifice between valve seat 17 and valve plug 11. Spring 10, compressed in the first part of the cycle, then reacts to lift members 43 and 8. These in turn lift bit 7 up off the bottom of the borehole and reseat shoulder 20 against shoulder 39.

The entire impact mass continues to move upwardly until stopped by gravitational and frictional forces. It will then fall to the bottom of the borehole with bit or cutting element 1 delivering a high energy impact due to the kinetic energy of the tool. The inner bit or cutting element 7 will strike the bottom of the borehole at the same time as the cutters of bit 1 due to the force exerted on the inner bit assembly upon contact of shoulder 39 with shoulder 20. It should be noted that at this moment the inner bit 7 is solidly coupled to the outer bit 1. The entire cycle is then repeated. Bits 1 and 7 drill the borehole cooperatively. The cutters of bit 7 impact the formation at the center of the borehole; while the cutters of outer bit 1 impact the formation at the outer edge of the borehole. Both bits are rotated simultaneously. The impact is sufficient to cause failure by crushing of the hardest rocks.

It should be noted that this tool does not incorporate a hammer and anvil as do most percussive type drilling tools. The impact is delivered directly to the face of the rack surface being drilled, rather than to an anvil.

Rotation or indexing of the bits is accomplished by maintaining torque on drill pipe 6 from the surface with conventional oil industry rotary drilling equipment. This torque is transmitted to the drilling tool through the spline joint formed by members 49 and 59. The tool in turn transmits torque to bit 1 directly and to bit 7 through spline joint 19 or by frictional contact of parts. Bits 1 and 7 will rotate when not in contact with the bottom of the borehole, resulting in the bits striking on a different surface of the hole bottom on each stroke of the percussive drilling tool.

The invention claimed is:

1. An apparatus for use in the rotary drilling of boreholes wherein a drilling fluid is circulated down through the apparatus comprising in combination: an upper tubular member adapted to be connected at its upper end to a rotatable pipe string, a tubular outer case mounted around said upper tubular member, first inter-connecting means between said upper tubular member and the upper portion of said case to enable longitudinally slidable motion therebetween and co-rotation therewith, an annular-type cutting element connected to the lower end of said case, a lower tubular member disposed within the lower portion of said case, second inter-connecting means between said lower tubular member and the lower portion of said case to enable longitudinally slidable motion therebetween and co-rotation therewith, an inner cutting element connected to the lower end of said lower tubular member and adapted to move within said annular cutting element, an upward facing surface defined on the upper end of said lower tubular member, a longitudinal passageway extending throughout said lower tubular member for the flow of drilling fluid therethrough, resilient means interposed between said lower tubular member and said case to bias said lower tubular member in an upward position relative to said case, valve means mounted within said case above said lower tubular memher and arranged to shut oif the upper end of said passageway when said lower tubular member is biased upward relative to said case whereby drilling fluid circulating through said apparatus will thrust said lower tubular member downward relative to said case, an internal downward facing shoulder on said case above said valve means whereby the pressure of said drilling fluid within said case will thrust said case upward upon closure of said valve means, and means to limit downward movement of said case relative to said lower tubular member at a position when said inner cutter cutting element is laterally opposite said annular cutting element.

2. An improved drilling tool for use in the rotary drilling of boreholes wherein a drilling fluid is circulated through the bore of the tool which comprises an upper tubular member attachable to the lower end of a rotary drill pipe string, an outer case slidably attached to said upper tubular member and co-rotatable therewith and containing a downward facing internal shoulder in the upper bore thereof, a lower tubular member slidable in said outer case below said upper tubular member and having a piston face on its upper end, a valve seat on the upper end of said lower tubular member, a tapered valve plug mounted on the end of a valve stem that is slidably attached to a bracket that is mounted in said outer case above said valve seat, said valve plug adapted to seat in said valve seat whereby the bore of said drilling tool is closed directing fluid above said valve seat onto said downward facing internal shoulder to move said outer case upward to unseat said valve plug diverting fluid pressure on said piston face on said lower tubular member to thrust said lower tubular member downward, an annular cutting element connected to the lower end of said sleeve, and a central cutting element connected to the lower end of said lower tubular member within said annular cutting element.

3. Apparatus for drilling boreholes wherein a drilling fluid is circulated through the bore of the apparatus comprising in combination an upper tubular member adapted to be connected on its upper end to a rotary drill pipe string, a longitudinally slidable outer case slidably connected to said upper tubular member and containing an upper and lower shoulder therein, a spline joint connecting said upper tubular member to said outer case, an annular cutting element having an axial bore and connected to said case, a lower longitudinally slidable tubular member slidably connected by a spline joint to said outer case having a shoulder on its outer periphery that mates with said lower shoulder of said outer case, a central cutting element connected to said lower tubular member to impact a formation simultaneous with said annular bit when said lower shoulder on said case mates with said shoulder on the outer periphery of said lower tubular member, a valve within said case that closes the fluid passageway through said tool whereby said case moves upward responsive to a pressure of drilling fluid on said upper shoulder of said outer case, and resilient means attached to said valve for biasing said valve upward to open said valve, whereby said outer case moves downward in response to force from a resilient member between said outer case and said lower tubular member, and said lower tubular member moves downward in response to pressure of the drilling fluid on the upper end of said lower tubular member.

References Cited in the file of this patent UNITED STATES PATENTS 842,049 Wolski Ian. 22, 1907 2,345,024 Bannister Mar. 28, 1944 FOREIGN PATENTS 529,208 Germany July 10, 1931 

2. AN IMPROVED DRILLING TOOL FOR USE IN THE ROTARY DRILLING OF BOREHOLES WHEREIN A DRILLING FLUID IS CIRCULATED THROUGH THE BORE OF THE TOOL WHICH COMPRISES AN UPPER TUBULAR MEMBER ATTACHABLE TO THE LOWER END OF A ROTARY DRILL PIPE STRING, AN OUTER CASE SLIDABLY ATTACHED TO SAID UPPER TUBULAR MEMBER AND CO-ROTATABLE THEREWITH AND CONTAINING A DOWNWARD FACING INTERNAL SHOULDER IN THE UPPER BORE THEREOF, A LOWER TUBULAR MEMBER SLIDABLE IN SAID OUTER CASE BELOW SAID UPPER TUBULAR MEMBER AND HAVING A PISTON FACE ON ITS UPPER END, A VALVE SEAT ON THE UPPER END OF SAID LOWER TUBULAR MEMBER, A TAPERED VALVE PLUG MOUNTED ON THE END OF A VALVE STEM THAT IS SLIDABLY ATTACHED TO A BRACKET THAT IS MOUNTED IN SAID OUTER CASE ABOVE SAID VALVE SEAT, SAID VALVE PLUG ADAPTED TO SEAT IN SAID VALVE SEAT WHEREBY THE BORE OF SAID DRILLING TOOL IS CLOSED DIRECTING FLUID ABOVE SAID VALVE SEAT ONTO SAID DOWNWARD FACING INTERNAL SHOULDER TO MOVE SAID OUTER CASE UPWARD TO UNSEAT SAID VALVE PLUG DIVERTING FLUID PRESSURE ON SAID PISTON FACE ON SAID LOWER TUBULAR MEMBER TO THRUST SAID LOWER TUBULAR MEMBER DOWNWARD, AN ANNULAR CUTTING ELEMENT CONNECTED TO THE LOWER END OF SAID SLEEVE, AND A CENTRAL CUTTING ELEMENT CONNECTED TO THE LOWER END OF SAID LOWER TUBULAR MEMBER WITHIN SAID ANNULAR CUTTING ELEMENT. 